The present invention relates to mobile communication system between a mobile station and a base station having a plurality of radio packet channels with different transmission rate with each other.
Conventionally, a mobile communication system for packet communication has a plurality of packet channels each having a single common transmission rate between a mobile station and a base station. In that system, when a free packet channel is selected, a duration for a packet transmission, or a number of frames for continuous transmission, is assigned.
On the other hand, in a future mobile communication system, such as IMT-2000 standard, packet channels having a plurality of transmission rates are possible. In that system, a packet channel having a desired transmission rate must be, first, selected, and then, a duration for a packet transmission can be assigned.
FIG. 1 shows a configuration of a mobile communication system, in which there are a plurality of communication cells each located adjacently, and each cell comprises a base station 2 and a plurality of mobile stations 1. A base station 2 is controlled by a control station 3 which is installed for a plurality of base stations 2. An assignment of a packet is controlled either by a base station 2 or a control station 3.
In a mobile communication system, when distance between a base station and a mobile station is defined, the higher transmission power is requested for the higher transmission rate. On the other hand, when a transmission rate of a packet is defined, the higher transmission power is requested, the longer the distance between a base station and a mobile station is.
Therefore, when the distance between a base station and a mobile station is long, and a transmission rate of a packet is high, the highest transmission power is requested.
However, when the distance between a base station and a mobile station is long, in other words, the mobile station locates close to a border of the cell of the own mobile station and the adjacent cell, the radio wave to/from said mobile station would affect interference to communication of adjacent cells.